Motor-compressor unit for refrigerating apparatus



Sept. 24, 1940. A. A. KUCHER MOTOR COMPRESSOR UNIT FOR REFRIGERATING APPARATUS Original Filed July 5l, 1954 5 Sheets-Sheet l M JAM, mw $022,

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A. A. KUCHER Original Filed July 3l, 1934 MOTOR COMPRESSOR UNIT FDR REFRIGERATING APPARATUS A. A. KUCHER Sept 2 94@ MOTOR COMPRESSDR UNIT FOR REFRIGERATING- APPARATUS s sheets-'sheet s Original Filed July 3l, 1934 Patented Sept. 24, 1940 UNITED STATES MOTOR-CONIPRESSOR UNIT FOR REFRIG- ERATING APPARATUS Andrew A. Kucher, Dayton, Ohio, assignor to General Motors Corporation, Dayton, Ohio, a corporation of Delaware Application July 31, 1934, Serial No. 737,786

Renewed August 19, 1937 Claims.

This invention relates to refrigerating-appa- A further object is to provide a novel unloadingy mechanism for a motor-compressor unit which is responsive to the increased starting torque produced by the usual type of electric motor.

Another object is to lprovide a motor-compressor unit in which one of the two main portions of the compressor is mounted for movement relative to its associated motor part, which movement may be utilized to control and operate unloading mechanism or other valve means within the compressor.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.

In the drawings:

Fig. 1 is a cross section of a motor-compressor unit embodying the present invention, the essential elements of a complete refrigerating apparatus being shown diagrammatically;

Fig. 2 is a partial cross section on line 2--2 of Fig. 1;

Fig.3 is a view corresponding to Fig. 1 of a modified form of the invention;

Fig. 4 is a partial cross'section on line 4-4 of 40 Fig. 3;

Fig'. 5 is a top View of a portion of the mechanism shown in Fig. 1;

Fig. 6 is a view corresponding to Fig. 5 with certain of the parts shown in different position;

Fig..7 is a view corresponding to Fig. 5 of a further modification of the invention; and

Fig. 8 is a view corresponding to Fig. 7 with certain of the parts illustrated in different positions..

Referring now to Fig. l, there is shown a refrigerating apparatus comprising a motor-compressor unit, generally designated as I0, which is adapted to deliver compressed refrigerant to `a condenser l2 by means of a conduit I4.. The

55 gaseous refrigerant is liquefied in the condenser I2 and accumulated in the receiver i6, whence liquid refrigerant'is delivered by a conduit I8 to an evaporator 20. 'I'he evaporator 20 may contain a oat valve/(not shown) for controlling the expansion of liquid refrigerant therein.4 The 5 suction conduit 22 delivers the gaseous refrigerant from the evaporator 20 to the inlet connection 24 of the compressor unit lll. A check valve 26 is inserted in the suction line for a purpose later to be described.

The motor-compressor unit comprises a metallic housing 28 having cooling fins 30 around its periphery and which is closed by a sealing member or cover plate 32. Pressed into the housing 28 is the stator 34 of an electric motor which may be of any well known type, for example, an alternating current induction motor and which has the characteristic of developing a substantially greaterl torque during starting than its normal running torque. A stationary shaft 36 is 20 mounted centrally in the 'cover plate 32 and in the toplof the housing 28, in the manner illustrated in the modification in Fig. 3. It is provided with a central bore throughout its length forming an outlet passage for compressed re- 25 frigerant. The shaft 36 forms a bearing for a drive sleeve 38,Which carries at its upper end the rotor 40 of the electric motor and which at its lower end is provided with an eccentric extergether by suitable fastening means and adapted 35' to form la compression chamber 54. Mounted on the eccentric bearing 42 and within the chamber 54 is an impeller 56 of annular form which is adapted to roll adjacentY the inner surface of the cylinder 50.

The inlet connection 24 is adapted to communicate with the suction side of the chamber 54 through an aperture 58 in the bottom plate 48. An outlet aperture (not shown) having a iiapper valve of the well known typeM is provided in the 45 upper plate 52 immediately above the compression side of the chamber 54. A bore 60 extends through the cylinder and the two plates 48 and 52 at a point angularly spaced in a clockwise direction from the port 58. A divided block 50 62 is located in a corresponding ,slot in the cylinder 50 and spring urged to engage the surface of the impeller 56 in all positions. The bottom plate 48 carries radially projecting therefrom an arm B4, which is adapted to be resiliently retained 55 against a spring pressed buer 66 by a tension 'spring 68 during normal operation of the compressor. Secured to the compressor body 46 is a cup shaped member 10 to provide an upper exhaust chamber 12 and to retain the springs 14 which urge the divider plate 62 inwardly. The compressor body 46 is supported on plate 44 by means of suitable anti-friction bearings 16, while the upper surface of the plate 44 is provided with a pair of sealing bosses 18 and 80. The form of the bosses 18 and 80 can be seen in Figs. 5 and 6.

In operation, it being understood that the electric motor is controlled by a suitable switch to operate the motor intermittently maintaining substantially constant temperature of the evaporator 20, the torque developed by the motor during the initial starting period is high. The spring 68 is of proper calibration to permit the body 46 of the compressor to rotate in a counterclockwise direction under the urge of the high starting torque, which in the present example is counter-clockwise, sufficiently to bring the port 60 in at least partial register with the inlet fitting 24, as shown in Fig. 6. With the parts in this position, it will ybe seen that as the driving sleeve 38 rotates, the eccentric bearing 42 will cause the impeller 56 to roll adjacent the inner surface of the cylinder 50 drawing in gaseous refrigerant through the port 58, which is maintained `in communication with the inlet fitting .24 and the bore 60 by a groove 82 in the boss 18.

In starting after a period of idleness, it frequently occurs that the lubricant for the com,- pressor which is maintained in the housing 28 to a level such as that indicated at 84, partially i'llls the compression chamber 54 resulting in a heavy load on the compressor. So long as the parts lie in the position shown in Fig. 6 during the production of high torque by the motor, a direct by-pass is provided from the outlet of the compressor through the bore 60 and-groove 82 to the inlet port 58, thus providing for unloading the compressor when starting. As soon as the abnormally high starting torque is reduced and the motor operates at its normal running torque and at its normal higher running speed, the

reduced torque permits the compressor body 46 -valve 26 functions to prevent high pressure gas from passing to the evaporator 20 during unloading when the bore 60 places the inlet connection 24 in communication with the high pressure gas in housing 28. A stop pin 83 is provided on cover plate 28 to limit the counter-clockwise rotation of the body 46 by engaging the arm 64. Preferably the pin 83 is formed with an external sleeve of soft rubber, felt or other resilient material to absorb vibration when the arm 64 is in contact therewith.

In the modification shown in Figs. 7 and 8, the use of the check valve 26 may be avoided without permitting high pressure gas to flow to the low side of the refrigerating system. In this modification, the parts of the motor-compressor unit are the same as those illustrated in Figs. 1 and 2 except that the bore 60' is located adjacent the port 58 but radially outward therefrom as shown in Fig. 7. The sealing bosses 18' and 80' are somewhat diiferently'formed as shown in Figs. 7 and 8 and the groove 82 which extends in a radial direction does not connect with the inlet connection 24. In operation of this modification, the bore 60 and the port 58 move to a position over the groove 82 during unloading, which as explained heretofore, provides a direct by-pass from the outlet to the inlet of the compressor. During normal running, port 58 lies over the inlet connection 24, while the bore 60 is sealed by the surface of the boss 18'.

It will be understood, of course, that the bosses and 80 serve merely to balance the sealing surface on the bottom of the plate 48, and that if desired, they may be omitted. Likewise, the thrust bearing between the plate 48 and the plate 44 may take the form of a plain bearing of limited area adjacent the shaft 36, it being essential only that friction between the plates 44 and 48 be maintained sufliciently low to permit free rotation of the compressor body 46 under the high pressure of the compressed gas in the interior of the housing 28.

Figs. 3 and 4 illustrate a further modification of the invention in which the automatic unloading feature is not provided, but in which the advantages of freedom from vibration of the motor-compressor unit are retained. In these figures, corresponding reference numerals indicate the corresponding parts illustrated in Figs. 1 and 2, the only difference being that the bypass port 6U is eliminated together with the sealing bosses -18 and 88 and the anti-friction bearing 16, although the latter may beretained if desired. The resilient anchorage in this modication takes a different form in that an arm 68 is secured to the cylinder 50 and is resiliently restrained by a pair of buffer springs 65 on opposite sides thereof, which are anchored to upstanding lugs 86 secured to the cover plate 32.

The operation of this form of the invention is substantially the same as the form illustrated in Figs. 1 and 2 with the exception that no unloading of the compressor during starting takes place. During both the starting and the normal running operation of the compressor, the torsional vibrations produced in the compressor are absorbed in oscillation of the compressor body 46 between springs 85, thus eliminating transfer of these vibrations to the housing 28.

While the form of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. In a motor-compressor unit, the combination of a stationary shaft, a motor having a rotor journaled on said shaft, a compressor having a high side and a low side and including a rotor also journaled on the shaft and a stator mounted for limited ro'tation about the shaft against movement limiting means, means for limiting the rotation of said compressor stator, a by-pass between said high side and low side opened by rotation of the compressor stator for unloading the compressor and means for automatically rotating said stator to open said by-pass during the starting period.

2. In a motor-compressor unit, the combination of a stationary shaft, a motor having a rotor journaled on said shaft, a compressor having a high side and a low side and including a rotor also journaled on the shaft and a stator mounted for limited rotation about the shaft, means for restraining the rotation of said compressor stator, a bypass formed at least partly in said stator and joining the high side and low side upon rotation of the compressor stator, said means for restraining including a resilient member.

3. In a compressor, a casing, a cylinder mounted to rotate about a main axis in said casing, a spring opposing rotation of said cylinder, a cylindrical piston withinl said cylinder and forming a compression chamber therewith, an eccentric within said piston mounted to rotate about said ymain axis, a divider block in said cylinder adjacent said piston, inlet meansand outlet means on said cylinder on opposite sides of said divider block, and a by-pass for fluid around said divider block when said cylinder is rotated against said spring.

4. In a compressor, a casing, a cylinder mounted to rotate about a stationary shaft in said casing, a spring opposing rotation of said cylinder, a cylindrical piston within said cylinder and forming a compression chamber therewith, an eccentric within said piston mounted to rotate about said stationary shaft, a divider block in said cylinder adjacent said piston, inlet means and outlet means on said cylinder on opposite sides of said divider block, and a by-pass formed in said casing to by-pass fluid around said divider block when said cylinder is rotated against said spring.

5. In a compressor, a casing, a cylinder mounted to rotate about a main axis in said casing, a spring opposing rotation of said cylinder, a rotary piston within said cylinder, inlet and outlet means in said casing, one of said means having sliding contact with said cylinder, and a by-pass on said cylinderarranged to connect with said one of said means upon partial rotation of said cylinder about said main axis.

6. In combination, a compressor having a cylinder, a piston movable relatively thereto, the arrangement being such that the* coefficient of starting friction between the cylinder` and the piston is greater than the coefcient of running friction therebetween, and means utilizing the greater coeicient of starting friction therebetween for opening a connection between the low and high pressure sides of Ithe compressor to unload the compressor. y

7. In a compressor having moving parts, said parts having a greater coeiiicient of starting friction than coeiiicient of running friction, and

' means utilizingthe difference between said co- 9. A compressor having a normally stationary cylinder having a rotary motion under starting friction conditions and a rotary piston, the cooperation between said cylinder and said piston being such that the coeflicient of the starting friction between said piston and cylinder is greater than the coeiicient of the running friction, and

means utilizing said greater coefficient of starting friction for unloading the compressor, said means including structure forming a by-pass by rotation of said cylinder, said cylinder being rotatably mounted to be turned into by-pass position by said starting friction and to by-pass closing position under running friction.

10. In combination, a compressor mechanism having a. high pressure side and a low pressure side comprising moving parts the movement of one of said parts being circular relatively to another of said parts, said parts being invfrictional contact with one another along a circular path and having a greater coeicient of starting friction than coeicient of running friction, and

means utilizing the difference between said starting and said running frictions for opening a connection between the high pressure and the low pressure sides of the compressor mechanismto vunload the compressor mechanism.

ANDREW A. KUCHER. 

